cleanup dead ast-borrowck / migrate-mode code.

src/librustc/arena.rs

@@ -86,7 +86,6 @@ macro_rules! arena_types {
                     rustc::infer::canonical::QueryResponse<'tcx, rustc::ty::Ty<'tcx>>
                 >,
             [few] crate_inherent_impls: rustc::ty::CrateInherentImpls,
-            [decode] borrowck: rustc::middle::borrowck::BorrowCheckResult,
             [few] upstream_monomorphizations:
                 rustc::util::nodemap::DefIdMap<
                     rustc_data_structures::fx::FxHashMap<

src/librustc/infer/mod.rs

@@ -93,6 +93,8 @@ impl SuppressRegionErrors {
     /// checks, so we should ignore errors if NLL is (unconditionally)
     /// enabled.
     pub fn when_nll_is_enabled(tcx: TyCtxt<'_>) -> Self {
+        // FIXME(Centril): Once we actually remove `::Migrate` also make
+        // this always `true` and then proceed to eliminate the dead code.
         match tcx.borrowck_mode() {
             // If we're on Migrate mode, report AST region errors
             BorrowckMode::Migrate => SuppressRegionErrors { suppressed: false },

src/librustc/lib.rs

@@ -100,7 +100,6 @@ pub mod infer;
 pub mod lint;
 
 pub mod middle {
-    pub mod borrowck;
     pub mod expr_use_visitor;
     pub mod cstore;
     pub mod dead;

src/librustc/middle/borrowck.rs

@@ -1,31 +0,0 @@
-use crate::ich::StableHashingContext;
-
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher,
-                                           StableHasherResult};
-
-#[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable)]
-pub enum SignalledError { SawSomeError, NoErrorsSeen }
-
-impl Default for SignalledError {
-    fn default() -> SignalledError {
-        SignalledError::NoErrorsSeen
-    }
-}
-
-impl_stable_hash_for!(enum self::SignalledError { SawSomeError, NoErrorsSeen });
-
-#[derive(Debug, Default, RustcEncodable, RustcDecodable)]
-pub struct BorrowCheckResult {
-    pub signalled_any_error: SignalledError,
-}
-
-impl<'a> HashStable<StableHashingContext<'a>> for BorrowCheckResult {
-    fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'a>,
-                                          hasher: &mut StableHasher<W>) {
-        let BorrowCheckResult {
-            ref signalled_any_error,
-        } = *self;
-        signalled_any_error.hash_stable(hcx, hasher);
-    }
-}

src/librustc/query/mod.rs

@@ -397,10 +397,6 @@ rustc_queries! {
     }
 
     BorrowChecking {
-        query borrowck(key: DefId) -> &'tcx BorrowCheckResult {
-            cache_on_disk_if { key.is_local() }
-        }
-
         /// Borrow-checks the function body. If this is a closure, returns
         /// additional requirements that the closure's creator must verify.
         query mir_borrowck(key: DefId) -> mir::BorrowCheckResult<'tcx> {

src/librustc/session/config.rs

@@ -478,14 +478,6 @@ impl BorrowckMode {
             BorrowckMode::Migrate => true,
         }
     }
-
-    /// Returns whether we should emit the AST-based borrow checker errors.
-    pub fn use_ast(self) -> bool {
-        match self {
-            BorrowckMode::Mir => false,
-            BorrowckMode::Migrate => false,
-        }
-    }
 }
 
 pub enum Input {

src/librustc/ty/context.rs

@@ -1435,12 +1435,6 @@ impl<'tcx> TyCtxt<'tcx> {
         self.queries.on_disk_cache.serialize(self.global_tcx(), encoder)
     }
 
-    /// If `true`, we should use the AST-based borrowck (we may *also* use
-    /// the MIR-based borrowck).
-    pub fn use_ast_borrowck(self) -> bool {
-        self.borrowck_mode().use_ast()
-    }
-
     /// If `true`, we should use the MIR-based borrowck, but also
     /// fall back on the AST borrowck if the MIR-based one errors.
     pub fn migrate_borrowck(self) -> bool {

src/librustc/ty/query/mod.rs

@@ -4,7 +4,6 @@ use crate::hir::def::{DefKind, Export};
 use crate::hir::{self, TraitCandidate, ItemLocalId, CodegenFnAttrs};
 use crate::infer::canonical::{self, Canonical};
 use crate::lint;
-use crate::middle::borrowck::BorrowCheckResult;
 use crate::middle::cstore::{ExternCrate, LinkagePreference, NativeLibrary, ForeignModule};
 use crate::middle::cstore::{NativeLibraryKind, DepKind, CrateSource};
 use crate::middle::privacy::AccessLevels;

src/librustc_mir/borrow_check/mod.rs

@@ -1932,41 +1932,20 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 }
             }
 
-            Reservation(wk @ WriteKind::Move)
+            Reservation(WriteKind::Move)
-            | Write(wk @ WriteKind::Move)
+            | Write(WriteKind::Move)
-            | Reservation(wk @ WriteKind::StorageDeadOrDrop)
+            | Reservation(WriteKind::StorageDeadOrDrop)
-            | Reservation(wk @ WriteKind::MutableBorrow(BorrowKind::Shared))
+            | Reservation(WriteKind::MutableBorrow(BorrowKind::Shared))
-            | Reservation(wk @ WriteKind::MutableBorrow(BorrowKind::Shallow))
+            | Reservation(WriteKind::MutableBorrow(BorrowKind::Shallow))
-            | Write(wk @ WriteKind::StorageDeadOrDrop)
+            | Write(WriteKind::StorageDeadOrDrop)
-            | Write(wk @ WriteKind::MutableBorrow(BorrowKind::Shared))
+            | Write(WriteKind::MutableBorrow(BorrowKind::Shared))
-            | Write(wk @ WriteKind::MutableBorrow(BorrowKind::Shallow)) => {
+            | Write(WriteKind::MutableBorrow(BorrowKind::Shallow)) => {
-                if let (Err(place_err), true) = (
+                if let (Err(_), true) = (
                     self.is_mutable(place.as_ref(), is_local_mutation_allowed),
                     self.errors_buffer.is_empty()
                 ) {
-                    if self.infcx.tcx.migrate_borrowck() {
+                    // rust-lang/rust#46908: In pure NLL mode this code path should
-                        // rust-lang/rust#46908: In pure NLL mode this
+                    // be unreachable (and thus we signal an ICE in the else branch here).
-                        // code path should be unreachable (and thus
-                        // we signal an ICE in the else branch
-                        // here). But we can legitimately get here
-                        // under borrowck=migrate mode, so instead of
-                        // ICE'ing we instead report a legitimate
-                        // error (which will then be downgraded to a
-                        // warning by the migrate machinery).
-                        error_access = match wk {
-                            WriteKind::MutableBorrow(_) => AccessKind::MutableBorrow,
-                            WriteKind::Move => AccessKind::Move,
-                            WriteKind::StorageDeadOrDrop |
-                            WriteKind::Mutate => AccessKind::Mutate,
-                        };
-                        self.report_mutability_error(
-                            place,
-                            span,
-                            place_err,
-                            error_access,
-                            location,
-                        );
-                    } else {
                     span_bug!(
                         span,
                         "Accessing `{:?}` with the kind `{:?}` shouldn't be possible",
@@ -1974,7 +1953,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         kind,
                     );
                 }
-                }
                 return false;
             }
             Activation(..) => {

src/librustc_mir/transform/elaborate_drops.rs

@@ -28,17 +28,7 @@ impl<'tcx> MirPass<'tcx> for ElaborateDrops {
         let param_env = tcx.param_env(src.def_id()).with_reveal_all();
         let move_data = match MoveData::gather_moves(body, tcx) {
             Ok(move_data) => move_data,
-            Err((move_data, _move_errors)) => {
+            Err(_) => bug!("No `move_errors` should be allowed in MIR borrowck"),
-                // The only way we should be allowing any move_errors
-                // in here is if we are in the migration path for the
-                // NLL-based MIR-borrowck.
-                //
-                // If we are in the migration path, we have already
-                // reported these errors as warnings to the user. So
-                // we will just ignore them here.
-                assert!(tcx.migrate_borrowck());
-                move_data
-            }
         };
         let elaborate_patch = {
             let body = &*body;

src/librustc_mir/transform/mod.rs

@@ -291,10 +291,6 @@ fn optimized_mir(tcx: TyCtxt<'_>, def_id: DefId) -> &Body<'_> {
     // execute before we can steal.
     tcx.ensure().mir_borrowck(def_id);
 
-    if tcx.use_ast_borrowck() {
-        tcx.ensure().borrowck(def_id);
-    }
-
     let (body, _) = tcx.mir_validated(def_id);
     let mut body = body.steal();
     run_optimization_passes(tcx, &mut body, def_id, None);